1. Field of the Invention
The present invention relates to an information medium evaluating method that reads data after rubbing a processing member onto a data recording surface of an information medium and evaluates the information medium based on the reading result.
2. Description of the Related Art
As one example of this type of information medium evaluating method, in Japanese Laid-Open Patent Publication No. 2002-260280 the present applicant discloses an evaluating method for an optical information medium (an optical disk) that deliberately damages the data recording surface of an optical disk (i.e., the incident surface for a laser beam used for recording and reproducing) and then evaluates the characteristics of the optical disk. In this evaluating method, the optical disk to be evaluated is loaded into a recording/reproducing apparatus (i.e., an optical disk drive) and the data is then reproduced (i.e., the data is read) to measure the BER (Bit Error Rate) for the reproduction signal. Next, an abrasion process that rubs an abrasion wheel (a wheel-shaped grindstone) against the data recording surface of the optical disk in accordance with an abrasion test (a taber abrasion test) standardized according to ISO 9352 is carried out.
More specifically, first, the optical disk to be evaluated is mounted onto the turntable of an abrasion tester with the data recording surface facing upward. Next, the turntable is rotated while pressing the abrasion wheel onto the optical disk on the turntable. When doing so, by rotating the optical disk by rotating the turntable, a ring-shaped region (a region that is concentric with the respective data recording tracks) on the data recording surface of the optical disk becomes damaged due to being rubbed by the abrasion wheel. Next, by loading the optical disk for which the abrasion process has been completed into a recording/reproducing apparatus and reproducing the data (i.e., reading the data), the BER of the reproduction signal is measured. After this, by comparing the measured BER before and after the abrasion process, as examples, optical disks where there is a large change in the BER are evaluated as being optical disks that are susceptible to damage or optical disks whose data becomes difficult to read due to damage. Conversely, optical disks where there is little change in the BER are evaluated as optical disks that are resistant to damage or optical disks whose data can be read even if damage has occurred. In this way, the evaluating process is completed for the optical information media.